/**
 * OSAmI: Open Source Ambient Intelligence
 * Copyright (C) 2010 Bull S.A.S.
 * Contact: osami-general@osami-commons.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 */

package org.osami.gateway.display.internal;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.felix.ipojo.annotations.Component;
import org.apache.felix.ipojo.annotations.Instantiate;
import org.apache.felix.ipojo.annotations.Invalidate;
import org.apache.felix.ipojo.annotations.Property;
import org.apache.felix.ipojo.annotations.Requires;
import org.apache.felix.ipojo.annotations.Validate;
import org.osami.gateway.alarm.IAlarm;
import org.osami.gateway.storage.IAlarmStorage;
import org.osgi.service.http.HttpContext;
import org.osgi.service.http.HttpService;
import org.osgi.service.http.NamespaceException;
import org.osgi.service.log.LogService;

@Component
@Instantiate
public class DisengageAlarmsServlet extends HttpServlet {

    /**
     * serial version UID.
     */
    private static final long serialVersionUID = 6630397067435699201L;

    @Property(value = Constants.DEFAULT_DISENGAGE_ALIAS)
    private String alias;

    @Requires
    private IAlarmStorage storage;

    @Requires
    private LogService logger;

    @Requires
    private HttpContext context;

    @Requires
    private HttpService httpService;

    @Validate
    public void start() throws ServletException, NamespaceException {
        this.httpService.registerServlet(this.alias, this, null, this.context);
    }

    @Invalidate
    public void stop() {
        this.httpService.unregister(this.alias);
    }

    private void doGetPost(final HttpServletRequest req,
                           final HttpServletResponse resp)
            throws ServletException, IOException {
        PrintWriter writer = resp.getWriter();

        writer.println("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">");
        writer.println("<html lang=\"en\">");

        // HTML Head
        // ---------------------------------------------------
        writer.println("<head>");
        writer.println("<title>Alarms disengaged at " + new Date() + "</title>");
        writer.println("<link href=\"/resource/css/designSensor.css\" rel=\"stylesheet\" type=\"text/css\" />");
        writer.println("</head>");

        // HTML Body
        // ---------------------------------------------------
        writer.println("<body>");

        printPageTitle(writer);

        // Process Alarm IDs
        String[] values = req.getParameterValues(Constants.DISENGAGED_ALARM);

        if (values != null) {
            printDisengagedAlarmsTable(writer, values);
        } else {
            // No parameters, do nothing
            // but prints an informative message
            writer.println("<p>");
            writer.println("No alarms selected to be disengaged.");
            writer.println("</p>");
        }

        printBackToDisplayAlarmsForm(writer);

        writer.println("<hr/>\n<a href=\"" + ServletPaths.INDEX + "\">Go back to main page</a>\n");
        writer.println("</body>");

        writer.println("</html>");
    }

    @Override
    protected void doGet(final HttpServletRequest req,
                         final HttpServletResponse resp)
            throws ServletException, IOException {

        doGetPost(req, resp);
    }

    @Override
    protected void doPost(final HttpServletRequest req,
                          final HttpServletResponse resp)
            throws ServletException, IOException {

        doGetPost(req, resp);
    }

    private void printDisengagedAlarmsTable(PrintWriter writer, String[] values) {

        writer.println("<table width='100%' cellpadding='0'>");
        // Print table headers
        writer.println("<thead><tr>");
        // Print each column name here
        printAlarmTableHeaders(writer);
        writer.println("</tr></thead>");

        // Print table body
        writer.println("<tbody>");

        for (String identifier : values) {
            try {
                synchronized (this.storage) {
                    IAlarm alarm = this.storage.remove(identifier);
//                  alarm.disengage();
                    printRowSuccess(writer, alarm);
                }
            } catch (Throwable throwable) {
                this.logger.log(LogService.LOG_WARNING, "Alarm disengagement for " + identifier + " has failed.", throwable);
                printRowFailure(writer, identifier, throwable.getMessage());
            }
        }

        writer.println("</tbody>");
        writer.println("</table>");
    }

    private void printPageTitle(PrintWriter writer) {
        writer.println("<h1>Alarms disengaged</h1><hr/>");
    }

    private void printBackToDisplayAlarmsForm(PrintWriter writer) {
        writer.println("<form action='" + Constants.DEFAULT_DISPLAY_ALIAS + "' method='POST'>");
        printRightAligned(writer, "<input type='submit' value='See Active alarms' />");
        writer.println("</form>");
    }

    private void printRightAligned(PrintWriter writer, String content) {
        writer.println("<div style='text-align:right;'>");
        writer.println(content);
        writer.println("</div>");
    }

    private void printAlarmTableHeaders(PrintWriter writer) {
        writer.println("<th>Identifier</th>");
        writer.println("<th>Severity</th>");
        writer.println("<th>Message</th>");
        writer.println("<th>Date</th>");
    }

    private void printRowSuccess(PrintWriter writer, IAlarm alarm) {
        // Green background
        writer.println("<tr style='background-color:#9AFE2E'>");
        printTableCell(writer, alarm.getIdentifier());
        printTableCell(writer, alarm.getSeverity().name());
        printTableCell(writer, alarm.getMessage());
        printTableCell(writer, alarm.getDate().toString());
        writer.println("</tr>");
    }

    private void printRowFailure(PrintWriter writer, String identifier, String message) {
        // Red background
        writer.println("<tr style='background-color:#F78181'>");
        String content = "Cannot disengage alarm (id:" + identifier + "): " + message;
        printTableCell(writer, 4, content);
        writer.println("</tr>");
    }

    private void printTableCell(PrintWriter writer, String content) {
        printTableCell(writer, 0, content);
    }

    private void printTableCell(PrintWriter writer, int colSpan, String content) {
        if (colSpan > 1) {
            writer.println("<td colspan='" + colSpan + "'>" + content + "</td>");
        }
        writer.println("<td>" + content + "</td>");
    }

}
